Relevance, materials and methods. The experimental scheme included the control group — the main diet (MD); group I (positive control) — MD + chlortetracycline (20%) 0.63 g per 1 kg of body weight for 20 days; group II — MD + gamma-octalactone at a dosage of 0.1 ml/kg of b.w./day; III group — MD + gammaoctalactone + chlortetracycline (20%).Results. In the course of research, the advantage of the live weight of experimental broilers over the control was established. The broilers that received gamma-octolactone + chlortetracycline with the main dietwere distinguished by the greatest live weight (16.5% more than in the control) . A similar situation was observed in terms of live weight gains. Broilers of the experimental groups ate more feed (by 3.23–8.47%), against the background of low feed consumption per 1 kg of live weight (by 6.38–10.6%) compared to the control. Broilers from group III had a higher content of erythrocytes (by 12.6–30.7%) and the weight of the spleen. The microbial profile of group III broilers (a combination of gamma-octalactone and chlortetracycline) was represented by microorganisms belonging to 4 phylum. The dominant phylum was Firmicutes (81.3%). Comparison with the control showed that the combination of substances reduced the number of bacteria of this phylum by 4.46%, against the background of an increase in the number of representatives of the Bacteroidetes phylum by 9.32% relative to the control. There was an increase in representatives of the genera Alistipes, Lactobacillus and unclassified genera of the family Clostridiales, while the number of representatives of unclassified genera of the family Ruminococcaceae decreased.

It is known that the inclusion of antibiotics in chicken feed leads to the development of resistance in bacteria. It is for this reason that the search for additives to alternative antibiotics becomes relevant. The ability of gamma-glucanolactone to inhibit various quorum systems (QS) LuxI/LuxR in bacteria has been demonstrated. Based on this, it can be assumed that the use of this substance in the diet will reduce infections in the intestines of poultry and improve the effects of broiler rearing. The aim of this work was to evaluate the microbiome of the iliac intestine of broilers when introducing gammaoctanolactone into the diet.The study was conducted using the sequencing method. Total DNA from samples of intestinal contents was isolated using the FastDNA ® Faecal Extraction Kit. Pair-end sequencing of DNA library amplicons was performed on the Illumina MiSeq Reagent Kit platform using the MiSeq v.2 Reagent Kit (500 cycles) (Illumina, San Diego, California, USA). The inclusion of gamma-octalactone in the diet of broilers at a dosage of 0.05 and 0,20 ml / kg w.m. / day contributes to an increase in the number of representatives of the phylum Firmicutes in the iliac intestine of poultry. The dosage of 0,05 ml / kg w.m. / day of gamma-octanolactone reduced the content of the genus Streptococcus by 4,21%; the dosage of 0,20 ml / kg w.m./ day of gammaoctanolactone increased by 10% representatives of the genera Lactobacillus and Turicibacter, relative to the control.

Coumarins are class of natural aromatic compounds based on benzopyrones (2H-1-benzopyran-2-ones). They are identified as secondary metabolites in about 150 different plant species. The ability of coumarins to inhibit cell-to-cell communication in bacterial communities (quorum sensing; QS) has been previously described. Coumarin and its derivatives in plant extracts are often found together with other small molecules that show anti-QS properties too. The aim of this study was to find the most effective combinations of coumarins and small plant-derived molecules identified in various plants extracts that inhibit QS in Chromobacterium violaceum ATCC 31532 violacein production bioassay. The coumarin and its derivatives: 7-hydroxycoumarin, 7.8-dihydroxy-4-methylcoumarin, were included in the study. Combinations of coumarins with gamma-octalactone, 4-hexyl-1.3-benzenediol, 3.4.5-trimethoxyphenol and vanillin, previously identified in oak bark (Quercus cortex), and eucalyptus leaves (Eucalyptus viminalis) extracts, were analyzed in a bioassay. When testing two-component compositions, it was shown that 7.8-dihydroxy-4-methylcoumarin, 4-hexyl-1.3-benzendiol, and gamma-octalactone showed a supra-additive anti-QS effect. Combinations of all three molecules resulted in a three- to five-fold reduction in the concentration of each compound needed to achieve EC50 (half maximal effective concentration) against QS in C. violaceum ATCC 31532.

No abstract

No abstract